Carbon tetrachloride (CC14) is a commonly used solvent in industry and in grain fumigation. It is known to be toxic to the mammalian liver, producing fatty infiltration following ingestion. We propose to study the mechanism of the hepatotoxic effects of CC14. Rats will receive CC14 by stomach tube. At various times afterwards, the livers of these animals will be studied with respect to lipid and lipoprotein content. The rate of synthesis of individual apolipoproteins (apoA-I, apoA-II and apoE) and albumin will be measured by pulse-labeling and immunochemical techniques. The level of translatable mRNA for these proteins will be quantified by in vitro translation. Furthermore, specific apoA-I and apoE RNA sequences will be quantified by hybridization to cloned cDNA probes that we have isolated in our laboratory. We will also develop an in vitro hepatocyte culture system and examine the effects of CC14 on apolipoprotein synthesis by the same techniques. As a morphological correlate of the effects of CC14 on apolipoprotein synthesis, we will study the immunocytochemical localization of the apolipoproteins by light and by electron microscopy. In the latter case, we will prepare Fab fragments of IgG against the apolipoprotein by pepain digestion. The Fab fragment will be coupled to horseradish peroxidase. Tissue section will studied by the indirect immunoperoxidase technique. Our biochemical and morphological studies in the rat will hopefully help elucidate the molecular basis of CC14-induced hepatic steatosis. Such a system will also serve as a model for drug-induced fatty liver disease.